SAPPHiRE & LHeC

1. cern.ch/accnet SAPPHiRE &LHeC Frank Zimmermann HF2012, FNAL, 16 November 2012 Thanks to R. Assmann, I. Bazarov, A. Bogacz, A. Chao, L. Corner, J. Ellis, E. Elsen, Z. Huang, J. Jowett, M. Klein, E. Nissen, K. Oide, D. Schulte, T. Takahashi, H. Tanaka, J. Teichert, K. Togawa, V. Telnov, M. Velasco, K. Yokoya, M. Zanetti, Y. Zhang,… work supported by the European Commission under the FP7 Research Infrastructures project EuCARD, grant agreement no. 227579

3. Large Hadron electron Collider (LHeC) RR LHeC: new ring in LHC tunnel, with bypasses around experiments RR LHeC e-/e+ injector 10 GeV, 10 min. filling time ERLLHeC: recirculating linac with energy recovery At 2012 CERN-ECFA-NuPECCLHeCworkshop ERL-LHeCwas selected as baseline (RR LHeC issues: HL-LHC schedule, tunnel work, interference)

4. LHeC Conceptual Design Report LHeC CDR published in J. Phys. G: Nucl. Part. Phys. 39 075001 (2012) ~600 pages

5. LHeC Higgs physics • precision coupling measurements (Hb, Hgg, H4l,…) • reduction of theoretical QCD-related uncertainties in pp Higgs physics • potential to find new physics at the cleanly accessible WWH (and ZZH) vertices

6. L-RLHeC road map to ≥1033cm-2s-1 luminosity of LR collider: HD~1.3 D. Schulte LHeC2010 (round beams) average e- current limited by energy recovery efficiency Ie=6.4 mA • maximize geometric • overlap factor • head-on collision • small e- emittance • qc=0 • Hhg≥0.9 highest proton beam brightness “permitted” (ultimate LHC values) ge=3.75 mm Nb=1.7x1011 bunch spacing 25 or 50 ns • smallest conceivable • proton b* function: • reduced l* (23 m → 10 m) • squeeze only one p beam • new magnet technology Nb3Sn • b*p=0.1 m

7. LHeC baseline (& pushed) parameters

8. LHeC ERL layout two 10-GeV SC linacs, 3-pass up, 3-pass down; 6.4 mA, 60 GeV e-’s collide w. LHC protons/ions A. Bogacz, O. Brüning, M. Klein, D. Schulte, F. Zimmermann, et al (C=1/3 LHC allows for ion clearing gaps)

9. LHeC: 3 passes, flexible momentum compaction arc lattice building block: 52 m long cell with 2 (10) dipoles & 4 quadrupoles LHeC flexible momentum compaction cell; tuned for small beam size (low energy) or low De (high energy) Alex Bogacz

10. prototype arc magnets eRHIC dipole model (BNL) LHeC dipole models (BINP & CERN) 5 mm gap max. field 0.43 T (30 GeV) 25 mm gap max. field 0.264 T (60 GeV)

11. SAPPHiRE

12. X(125) seems to strongly couple to gg LHC ATLAS result LHC CMS result TeV Run-II result

13. a new type of collider? s-channel production; lower energy; no e+source g t, W, … H another advantage: no beamstrahlung → higher energy reach than e+e- colliders g ggcollider Higgs factory

14. LHC – the first photon collider! ultra-peripheral photon-photon interaction in Pb-Pb collisions at ALICE thanks to John Jowett CERN Courier, November 2012

15. in LHC p-Pbg-gcollisions David d’Enterria, 17 October 2012 thanks to John Jowett

16. in LHC p-Pbg-g collisions David d’Enterria, 17 October 2012 ~34 events / yr with lots of effort

17. ggcollider based on e- combining photon science & particle physics! few J pulse energy with l~350 nm K.-J. Kim, A. Sessler Beam Line Spring/Summer 1996

18. which beam & photon energy / wavelength? examplex≈ 4.3 (for x>4.83 coherent pair production occurs) 66 GeV ECM,max GeV Ephoton ~3.53 eV , l~351 nm

19. Higgs gg production cross section Left: The cross sections for gg→ h for different values of Mhas functions of ECM(e−e−). Right: The cross section for gg→ h as a function of Mhfor three different values of ECM(e−e−). Assumptions: electrons have 80% longitudinal polarization and lasers are circularly polarized, so that produced photons are highly circularly polarized at their maximum energy.

20. Reconfiguring LHeC → SAPPHiRE SAPPHiRE* ggHiggs factory LHeC-ERL *Small Accelerator for Photon-Photon Higgs production using Recirculating Electrons

21. SAPPHiRE: a Small ggHiggs Factory scale ~ European XFEL, about 10-20k Higgs per year SAPPHiRE: Small Accelerator for Photon-Photon Higgs production using Recirculating Electrons

23. SAPPHiREgg luminosity M. Zanetti luminosity spectra for SAPPHiRE as functions of ECM(gg), computed using Guinea-Pig for three possible normalized distancesr≡lCP-IP/(gsy*) (left) and different polarizations of in-coming particles (right)

24. Energy loss on multiple passes The energy loss per arc is For r=764 m (LHeC design) the energy loss in the various arcs is summarized in the following table.e- lose about 4 GeV in energy, which can be compensated by increasing the voltage of the two linacs from 10 GV to 10.5 GV. We take 11 GV per linac to be conservative.

25. Emittancegrowth The emittance growth is with Cq=3.8319x10-13 m, and r the bending radius. For LHeCRLA design with lbend~10 m, and r=764 m, <H>=1.2x10-3 m [Bogacz et al]. At 60 GeV the emittance growth of LHeCoptics is 13 micron, too high for our purpose, and extrapolation to 80 GeV is unfavourable with 6th power of energy. From L. Tengwe also have scaling law , which suggests that by reducing the cell length and dipole length by a factor of 4 we can bring the horiz. norm. emittance growth at 80 GeV down to 1 micron. DeN,x≤1 mm: reduced LHeC cell length 52 → 13 m will do Valery Telnov thinks this scaling is too optimistic

26. reference

27. flat polarized electron source • target ex/ey~ 10 • flat-beam gun based on flat-beam transformer concept of Derbenev et al. • starting with ge~4-5 mm at 0.5 nC, injector test facility at Fermilab A0 line achieved emittances of 40 mm horizontally and 0.4 mm vertically, with ex/ey~100 • for SAPPHiREwe only need ex/ey~10, but at three times larger bunch charge (1.6 nC) and smaller initial ge~1.5 mm • these parameters are within the present state of the art (e.g. the LCLS photoinjector routinely achieves 1.2 mm emittance at 1 nCcharge) • however, we need a polarized beam… Valery Telnov stressed this difficulty

28. can we get ~ 1-nC polarized e- bunches with ~1 mm emittance? ongoing R&D efforts: low-emittance DC guns (MIT-Bates, Cornell, SACLA?, JAEA, KEK…) [E. Tsentalovich, I. Bazarov, et al] polarized SRF guns (FZD, BNL,…) [J. Teichert, J. Kewisch, et al]

29. Cornell DC gun The answer is a qualified 'yes‘. Presently we have demonstrated 90% emittances of 0.5mm-mrad at 80pC/bunch and 0.2mm-mrad at 20pC/bunch for 2ps rms bunches with the gun voltage and photocathode we are using. The scaling with charge is bunch_charge^(1/2) meaning that numbers around 2-3 mm-mrad should be doable from our gun today [for 1-2 nC charge]. We are working on further improving our gun and laser shaping, expecting to halve the emittance even when using the same photocathodes we have today. Better photocathodes automatically translate into smaller emittances and many pursue this venue as well Ivan Bazarov, 7 Nov 12 SACLA pulsed “DC” gun I think our gun almost meets your requirement except for the repetition rate Hitoshi Tanaka, 7 Nov 12

30. Rossendorf polarized SRF gun Für2013 wollen wir die 2. Version der SRF-Gun in Betrieb nehmen. Das neue Cavity erreichte im Test am Jlab ein Peakfeld von 43 MV/m. Mit diesen Werten sollten wir 1 nC Ladung mit 500 kHz Reprate im CW (0.5 mA average current) erreichen. Die Emittanz könnte etwa 2 µm sein. Auf 1 µm könnte man etwa kommen, wenn wir vom Gausslaser zum Flat-top übergehen (analog zu PITZ/XFEL gun). Mit der Inbetriebnahme der 2. Gun, wird dann auch das Kathodentransfersystem ausgetauscht, und wir denken dann auch die GaAs-Kathoden zu testen. Ergebnisse dann im Jahr 2014. JochenTeichert, 12 Nov 12 • BNL QWT polarized SRF gun • simulations of 5 mm emittanceat 10 nCwith 112 MHz gun Tor Raubenheimer, 14 Nov 2012

31. laser progress: example fiber lasers power evolution of cw double-clad fiber lasers with diffraction limited beam quality over the past decade: factor 100 increase! Source: Fiber lasers and amplifiers: an ultrafast performance evolution, Jens Limpert, Thomas Schreiber, and Andreas Tünnermann, Applied Optics, Vol. 49, No. 25 (2010)

32. passive optical cavity → relaxed laser parameters K. Moenig et al, DESY Zeuthen

33. LALMightyLaserexperiment at KEK-ATF non-planar high finessefour mirror Fabry-Perot cavity; first Compton collisions observed in October 2010 I. Chaikovska, N. Delerue, A. Variola, F. Zomer et al Vacuum vessel for Fabry-Perot cavity installed at ATF Optical system used for laser power amplification and to inject laser into FPC Plan: improve laser and FPC mirrors & gain several orders Comparison of measured and simulated gamma-ray energy spectra from Compton scattering Gamma ray spectrum for different FPC stored laser power I. Chaikovska, PhD thesis to be published

34. self-generated FEL g beams (instead of laser)? wiggler converting some e- energy into photons (l≈350 nm) e- (80 GeV) e- (80 GeV) e-bend optical cavity mirrors e- bend Compton conversion point gg IP “intracavitypowers at MW levels are perfectly reasonable” – D. Douglas, 23 August 2012 • example: • lu=200 cm, B=0.625 T, Lu=100 m, U0,SR=0.16 GeV, 0.1%Pbeam≈25 kW scheme developed with Z. Huang

35. modified design approach Yuhong Zhang JLAB • thin laser target • eliminates most useless and harmful soft γ photons from multiple Compton scattering • relaxed laser requirements (~factor 10) • high luminosity achieved through an increase of bunch repetition rate and higher e- beam current (~factor 10) with multi-pass recirculating linacand energy recovery

36. SAPPHiRE “fits” on the SLAC site

37. arc magnets -17 passes! 5.6 GeV 15.8 26.0 36.2 46.0 55.3 63.8 71.1 71.1 63.8 55.2 46.0 36.2 26.0 15.8 5.6 HERA Tunnel Filler beam 1 beam 2 75.8 GeV laser or auto-driven FEL r=564 m for arc dipoles (probably pessimistic; value assumed in the following) IP 2x8+1 arcs 20-MV deflecting cavity (1.3 GHz) 20-MV deflecting cavity 3.6 GeV linac real-estate linac Gradient ~ 10 MV/m total SC RF = 10.2 GV 3.6 GeV Linac (1.3 GHz) 2x1.5 GeV linac F. Zimmermann, R. Assmann, E. Elsen, DESY Beschleuniger-Ideenmarkt, 18 Sept. 2012 0.5 GeV injector

38. Edward Nissen Possible Configurations at JLAB Town Hall meeting Dec 19 2011 85 GeV Electron energy γ c.o.m. 141 GeV 103 GeV Electron energy γ c.o.m. 170 GeV

39. Possible Configurations at FNAL Edward Nissen Tevatron Tunnel Filler Options 1) • Both versions assume an effective accelerating gradient of 23.5 MeV/m • Option 1: would require more civil construction, but would only require two sets of spreader /recombiner magnets, and only two linacs, for greater simplicity. • Option 2: would require 10 sets of spreader /recombiner magnets and 5 linacs but would achieve better beam parameters IP 5 Linacs 2) 2 Linacs IP

40. LHeC R&D items • SC IR final “half quadrupole” • IR beam pipe • RF cryostat incl. cavity & coupler • dedicated LHeC ERL test facility • proto collaboration for detector

41. SAPPHiRE R&D items • gginteraction region • large high-finesse optical cavity • high repetition rate laser • FEL in unusual regime • separation scheme for beams • circulating in opposite directions • polarized low-emittance e-gun • detector

42. Conclusions • SAPPHiRE+LHeCare exciting &popular projects • SAPPHiRE and/or LHeCmay be someof the cheapest possible options to further study the Higgs (cost ~1BEuro scale); feasible, but, esp. SAPPHiRE,not easy • JLAB thin-target approach is interesting option • LHeCis necessarily based at CERN • SAPPHiRE matches infrastructure, expertise & sites of many HEP or former or future HEP laboratories (DESY, SLAC, KEK, FNAL, JLAB,…)

43. flying into Chicago on Tuesday night • lots of lights - ideal place for a ggcollider?! thank you for your attention!

44. References for LHeC and SAPPHiRE: [1] S. A. Bogacz, J. Ellis, L. Lusito, D. Schulte, T. Takahashi, M. Velasco, M. Zanetti, F. Zimmermann, ‘SAPPHiRE: a Small Gamma-Gamma Higgs Factory,’ arXiv:1208.2827 [2] D. Asner et al., ‘Higgs physics with a gamma gamma collider based on CLIC I,’ Eur. Phys. J. C 28 (2003) 27 [hep-ex/0111056]. [3] J. Abelleira Fernandez et al, ‘A Large Hadron Electron Collider at CERN - Report on the Physics and Design Concepts for Machine and Detector,’ Journal of Physics G: Nuclear and Particle Physics 39 Number 7 (2012) arXiv:1206.2913 [physics.acc-ph]. [4] Yuhong Zhang, ‘Design Concept of ag-gCollider-Based Higgs Factory Driven by Energy Recovery Linacs,’ JLAB Technote JLAB-TN-12-053, 31 October 2012 [5] E. Nissen, ‘Optimization of Recirculating Linacs for a Higgs Factory,’ prepared for HF2012 [6] J. Limpert, T. Schreiber, A. Tünnermann, ‘Fiber lasers and amplifiers: an ultrafast performance evolution,’ Applied Optics, Vol. 49, No. 25 (2010)

45. back-up slides

47. linac features LHeClinac 5x longer with 4x the energy gain (cavity filling factor 0.50 vs 0.64) eRHIClinac: no focusing LHeClinac: ~100 quadrupoles increase multi-pass BBU threshold LHeClinacquadrupole options: - electromagnets with indiv. powering - clustered electromagnets - permanent magnets Q0: a key parameter !

48. LHeC electrical power budget design constraint: total el. power <100 MW